Cisco IOS SNMP v3 config commands and matching snmpwalk flags
SNMP v3 IOS config commands and snmpwalk examples
myrouter(config)#snmp-server user snmpusername snmpgroupname v3
myrouter(config)#snmp-server group snmpgroupname v3 noauth
nmsuser@nmshost~$ snmpwalk -v3 -u snmpusername -l noAuthNoPriv 192.168.2.3 1.3.6.1.2.1.1.9
nmsuser@nmshost~$ snmpwalk -v3 -u snmpusername -l noAuthNoPriv 192.168.2.3 1.3.6.1.2
myrouter(config)#snmp-server user snmpusername snmpgroupname v3 auth sha snmppassword
nmsuser@nmshost~$ snmpwalk -v3 -u snmpusername -l authNoPriv -a sha -A snmppassword 192.168.2.3 1.3.6.1.2
nmsuser@nmshost~$ snmpwalk -v3 -u snmpusername -l noAuthNoPriv 192.168.2.3 1.3.6.1.2
myrouter(config)#no snmp-server group snmpgroupname v3 noauth
myrouter(config)#snmp-server group snmpgroupname v3 auth
nmsuser@nmshost~$ snmpwalk -v3 -u snmpusername -l noAuthNoPriv 192.168.2.3 1.3.6.1.2
nmsuser@nmshost~$ snmpwalk -v3 -u snmpusername -l authNoPriv -a sha -A snmppassword 192.168.2.3 1.3.6.1.2.1
myrouter(config)#snmp-server group snmpgroupname v3 priv
myrouter(config)#snmp-server user snmpusername snmpgroupname v3 auth sha snmppassword priv aes 128 cryptopassword
nmsuser@nmshost~$ snmpwalk -v3 -u snmpusername -l authPriv -a sha -A snmppassword -x aes -X cryptopassword 192.168.2.3 1.3.6.1.2
nmsuser@nmshost~$ snmpwalk -v3 -u snmpusername -l authNoPriv -a sha -A snmppassword 192.168.2.3 1.3.6.1.2.1
nmsuser@nmshost~$ snmpwalk -v3 -u snmpusername -l authPriv -a sha -A snmppassword -x aes -X cryptopassword 192.168.2.3 1.3.6.1.2.1
As far as I know, you cannot get the snmppassword or cryptopassword back after you have entered it. You can execute
show snmp-server user snmpuser
and that will give some information but not the password or crypto passphrase.